Its just the way I hear his music. When I saw hammeredklavier post the quote from Brahms stating that true dissonance is found in Bach and Mozart, not so much Beethoven, I felt vindicated in my belief, because that is what I hear as well, and obviously to some extent Bernstein felt this way too. So I don't think it is just in my head, there is something to it. That said obviously Beethoven had other strengths (he was after all Bernstein's favorite composer), he is widely regarded as among the greatest composers, and his music has been incredibly successful. Whether his harmonic language was exactly as he wanted it, or just the best he could do, I think is speculation.
I will say I feel that Wagner is simply outstanding in some ways from a harmonic standpoint. If you want to call him on par with the greatest harmonic masters I respect your view, and maybe you're right. There are elements of Wagner, that I would best describe as dazzling, shimmering and attractive in ways that Brahms music is not. However I see these elements as essentially what I would describe as effects more so than the strong substantive harmonic forms that Brahms created. Previously in another thread I made the point that fools gold can seem to shine brighter than real gold, and I compared Brahms to gold. Calling Wagner fools gold goes too far as criticism, but in my view his strengths are more closely related to surface effects more so than the depth we hear in Brahms best compositions. They are very different composers, I stand in awe of some of the moments of Wagner's compositions, which were unprecedented and brilliant, but if we look at their work as a whole I still feel Brahms was the better composer over all, and I find his use of harmony more subtle and often emotionally complex in ways Wagner is not. We tend to know what Wagner is trying to evoke through his use of harmony, with Brahms the effect is often more complex, layered and ambiguous.
I respect your perceptions, which I think come down largely to your preference for Brahms's artistic goals. I do think it's very problematic to try to compare these composers in any specific respect; the heroes of the "conservatives" and "progressives" of 1870 have settled down comfortably beside each other as poles of a continuum we simply called "German Romanticism," but we can certainly understand that they were doing very different things. I'm absolutely certain that neither of them could have done the sorts of things the other did, and I'm sure they believed that too. Brahms studied Wagner's scores, once called himself - and not sarcastically - a "Wagnerite," and wanted to attend the Parsifal
premiere, deciding against it only because he feared his presence might cause a disturbance. Wagner acknowledged Brahms's success with traditional forms and appreciated that his own musical idioms, born of dramatic necessity, were not essentially what was required for symphonic writing and shouldn't be imported into absolute music carelessly. Those symphonies Wagner hoped to write at the end of his life would have been very unlike those of Brahms, but that may be all we can guess about them.
I think your statement, "There are elements of Wagner, that I would best describe as dazzling, shimmering and attractive in ways that Brahms music is not. However I see these elements as essentially what I would describe as effects more so than the strong substantive harmonic forms that Brahms created,"
indicates a perfectly legitimate preference for Brahms's basic artistic approach. You probably haven't been motivated to look closely enough at Wagner's constructive skills, and the key role his harmony plays, to see just what he's up to. In my experience, most listeners have not; we don't easily identify his free, overlapping, dovetailing, morphing, fragmentary, motif-driven structures as they flow out of his dramatic situations. Unlike those of absolute music in a Classical mold, Wagner's forms are not generally intended to call attention to themselves. Through-composed music drama and the symphony aren't just apples and oranges, they're apples and aardvarks. Probably the nearest we can come to a reasonable point of comparison is to look at Wagner's overtures, preludes, interludes and other orchestral passages from the operas, where his need to expand his ideas quasi-symphonically is expressed. But the comparison breaks down pretty quickly. What we find there is an incredible variety of innovative structures, along with a full range of harmonic techniques, whose relationship to Classical models ranges from deliberate and clear to virtually nonexistent. I think of Brahms's (attributed) remark on hearing the Siegfried Idyll,
"Yes, yes...But one can't have music like that ALL the time!" I'm sure he realized that as Wagner progressed from work to work he was constantly inventing music that wasn't
"like that," music in notable ways not like any heard before, including his own. The desolate, faltering, dissoving harmonies of Parsifal
's Act 3 prelude open up territory Brahms had no point of contact with, but Berg and Schoenberg certainly perceived as an inviting door.
Wagner himself once said that he was only a mediocre composer unless he had a great poetic/dramatic idea to inspire him. I guess that makes him a quintessential Romantic, in contrast to Brahms, who kept his sights on what he felt was a timeless structural ideal. If Brahms had any "poetic ideas" in mind for his symphonies, chamber music and piano works, he kept them to himself. His genius was to find in this severe aesthetic a channel for his own very personal sensibility. And that makes him a true Romantic too, whether he wanted to be or not.
Brahms and Wagner, by the way, are two of my top composers. I find comparing them fascinating, if only to bring home the realization that they're scarcely comparable.